Apparatus for inhalation tests with rodents

ABSTRACT

A cigarette smoke inhalation device for rodents consists of a catheter placed in the throat of the rodent so as to exclude nasal respiration, a bit surrounding the catheter allowing gripping by the teeth of the rodent so as to maintain the catheter in position, and a three way valve acting as a cigarette holder with means for controlling the admixture of air to the cigarette smoke.

United States Patent [72] Inventor Wolfgang Karl Joachim Heldt 1,404,408 1/ 1922 Rosling 128/ 147x Wasser, Breisgau, Germany 2,797,682 7/1957 Kannenberg 128/2 [2]] App1.No. 665,604' 2,820,457 l/1958 Philips 128/351 [22] Filed Sept. 5,1967 3,017,880 1/1962 Brook 128/145.5 [45] Patented Jan. 5,1971 3,265,062 8/1966 Hesse 123/145.8 Assisnee Gallaher Limited OTHER REFERENCES London, England [32] Priority May 11, 1967 fg T gflg hfi a f Bums 33 Great Britain N 21 995/67 SCIENCE NEWS, Vol. 92, No. 7, pp. 158 159, August I 1 12,l967,(CopyinGr.330,l3l- 171 Primary Examiner-Richard A. Gaudet [54] APPARATUS FOR INHALATION TESTS WITH Assistant Examiner- Kyle L. Howell RODENTS Attorney-Fritz G. Hochwald & Christen & Sabol 3 Claims, 2 Drawing Figs.

[52] US. Cl 128/2, 128/2.08, 128/211,128/351, l31/l71, 131/198 [51] Int. Cl A6lb 10/00 [50] Field of Search 128/2, ABSTRACT: A cigarette smoke inhalation device for rodents 203-409, consists of a catheter placed in the throat of the rodent so as to 21 3 172 exclude nasal respiration, a bit surrounding the catheter allowing gripping by the teeth of the rodent so as to maintain the [56] References cued catheter in position, and a three way valve acting as a cigarette UN ED TA E PATE T holder with means for controlling the admixture of air to the 733,026 7/1903 Goldan 128/209 cigarette m k ONE'WIY 0NE-WAY 5 VALVE vALv 6 PATENTED JAN Si n 3,552,380

. ONE-WAY 0 -WAY 9 7VALVE v E 6 APPARATUS FOR INHALATION TESTS WITH RODENTS The invention relates to an apparatus suitable for inhalation tests with rodents, particularly rabbits.

In accordance with the invention, there is provided apparatus for inhalation tests with rodents, which comprises a catheter to be placed in the throat of the experimental animal over its larynx so as to exclude nasal respiration, the catheter having a stationary bit.

A wide variety of methods and apparatus have been used to determine the effect of aerosols and particularly tobacco smoke, preferably cigarette smoke, on'rodents such as rats and rabbits.

Thus when using rabbits as the experimental animals for the smoke tests, for example, an airtight chamber in which the animal is placed has been filled with cigarette smoke by smoking down a cigarette in the actual chamber by the use of low pressure and leaving the animal exposed to the smoke for a given time. v

In another method the experimental animal is placed in an immobilizing cage which is hermetically sealed and can be connected to a vacuum system. At the front of the cage is an electromagnetically controlled valve mechanism which connects the fresh air pipe or, during the smoking phase, the cigarette pipe to the cage at given intervals.

Further tests have been carried out by sucking smoke and/or fresh air through a broad pipe with collars fitted into the wall of the pipe, the heads of the experimental animals being placed in the collars with an airtight seal round their necks. ln this way the animals were compelled to breath in the smoke and air mixture flowing through the pipe for a given time.

However, these known methods provide no comparison with the habits of a typical cigarette smoker (oral inhalation of cigarette smoke), for the experimental animals very probably draw extremely shallow breaths during the experiment and moreover breath through the nose, which acts as a filter and largely prevents coarser particles from entering the respiratory tract in a way that is not comparable with oral inhalation.

Even short term treatments of rabbits with a given quantity of smoke using apparatus capable onlyof providing for forced respiration by anesthetized rabbits do not produce accurate results suitable for comparison with human smoking. In the light of these known methods the problem was therefore to find a method or an apparatus enabling the nasal respiration of experimental animals to be excluded.

For this purpose an apparatus was constructed which sealed the nasal orifices of the rabbits by means of a plastic rubber material. With this, however, reliable working could be achieved only for a short time, with the aid of a rubber band drawn tightly over the nose. But with this method it was not possible to ascertain how deeply the animal was beathing.

A new apparatus for inhalation tests with rodents, particularly rabbits, has now been developed. The apparatus is characterized in that it comprises a catheter (rubber tube) to be placed in the animal's throat over the larynx so as to exclude nasal respiration, the catheter being fitted with a bit and being connected to a three way valve.

The preferred apparatus according to the invention is illustrated in the accompanying drawings and described in detail in the description that follows.

. ln the "drawings:

FIG. 1 shows, diagrammatically in top plan view, the catheter with the three way valve; and

FIG. 2 shows diagrammatically in transverse section, the bit drawn over the catheter.

In FIG. 1 the rubber catheter l is provided with a piece of softer rubber 2 which is placed over the larynx of the experimental animals so as to seal it off firmly and tightly against nasal respiration and against atmosphere. To prevent any change in the position of the catheter, a bit 3 is drawn over it and locked to it. The incisor teeth of the animal are placed in the grooves 10, at the top and bottom edges of the bit in FIG.

2. The outer end of the catheter l is connected to the three way valve 4. The valve housing 4 has two connecting stubs, one of which Is in the form 0 a cigarette holder 5 and the other of which is provided for connection to a measuring instrument (spirometer). The stubs 5 and 6 may be fixed by screws or the like. To provide a satisfactory control of inhalation and exhalation, two sheets of metal or plastics are mounted as non return valves, so that when the animal breathes in the valve 7 opens and the valve 8 closes and when the animal breathes out the valves behave in the reverse manner.

In order that air can be mixed with the smoke produced by the burning cigarette, a hole 9 of about 1.5 mm. is made through the valve housing 4 and the stub 5 acting as a cigarette holder. By turning the stub 5 about a longitudinal axis the two apertures can be brought more or lessinto registry, thereby regulating the proportion of air to be admixed into the cigarette smoke.

The three way valve 4 may be made of metal or plastics It is advisable to use transparent plastics so that the density of the smoke can be checked.

The bit 3 firmly fitted over the catheter tube 1 and containing grooves 10 is also made of rubber which is hard and resistant or else is made of a strong, relatively hard but resilient plastics material such as polyvinylchloride, in order that it can withstand biting by the animal but does not damage the animals teeth.

The advantage of the illustrated apparatus is firstly that the animal can be directly provided with fresh cigarette smoke, and secondly that, with the aid of the holes acting as mixing nozzles, the extent to which the fresh cigarette smoke is diluted with fresh air or any gas or gas mixture can be varied according to requirements. Moreover exact dosing is possible, for example by controlling the number of cigarettes. In addition, the depth of all the breaths drawn can readily be measured during the smoke test.

lclaim:

1. Apparatus for inhalation tests of cigarette smoke with rodents comprising a catheter tube having a length sufficient for insertion into the throat of a rodent and including elastomeric material surrounding one end of the tube and of a size adapted for establishing communication between the larynx and one end of the tube to allow the passageof gases only through said tube, bit means medially mounted on said tube and adapted for engagement with the teeth of a rodent to position said catheter tube, valve means including first and second stub means and one-way valving means, the first stub means including a tubular housing and a tubular holder for connection with a cigarette rotatably mounted in the tubular housing, said holder and housing havinga pair of generally aligned openings for admixing atmospheric air with gas received from a cigarette, the second stub means being adapted for communication with a measuring device, said one-way valving means including 'fir'st and second one-way valves disposed between the other end of said catheter tube and respectively said first stub means and said second stub means and arranged for admitting into said tube only gas received from the first stub means and to direct gas from the tube only to the second stub means. g

2. The invention defined in claim], wherein said bit means comprises a block of relatively hard elastomeric material surrounding said catheter tube and being provided with grooves on opposite sides for engagement by the teeth of a rodent.

3. The invention defined in claim 1, wherein said catheter tube is provided with a piece of elastomeric material at said one end, said bit means includes a block of elastomeric material surrounding said tube, and said valve means includes a T-shaped hollow housing, the base of said housing being in communication with the other end of said tube, said first and second stub means projecting respectively from the opposite arms of said housing. 

1. Apparatus for inhalation tests of cigarette smoke with rodents comprising a catheter tube having a length sufficient for insertion into the throat of a rodent and including elastomeric material surrounding one end of the tube and of a size adapted for establishing communication between the larynx and one end of the tube to allow the passage of gases only through said tube, bit means medially mounted on said tube and adapted for engagement with the teeth of a rodent to position said catheter tube, valve means including first and second stub means and oneway valving means, the first stub means including a tubular housing and a tubular holder for connection with a cigarette rotatably mounted in the tubular housing, said hoLder and housing having a pair of generally aligned openings for admixing atmospheric air with gas received from a cigarette, the second stub means being adapted for communication with a measuring device, said one-way valving means including first and second one-way valves disposed between the other end of said catheter tube and respectively said first stub means and said second stub means and arranged for admitting into said tube only gas received from the first stub means and to direct gas from the tube only to the second stub means.
 2. The invention defined in claim 1, wherein said bit means comprises a block of relatively hard elastomeric material surrounding said catheter tube and being provided with grooves on opposite sides for engagement by the teeth of a rodent.
 3. The invention defined in claim 1, wherein said catheter tube is provided with a piece of elastomeric material at said one end, said bit means includes a block of elastomeric material surrounding said tube, and said valve means includes a T-shaped hollow housing, the base of said housing being in communication with the other end of said tube, said first and second stub means projecting respectively from the opposite arms of said housing. 